Proton Total Marrow Irradiation-Based Conditioning for Allogeneic Hematopoietic Stem Cell Transplantation in High-Risk Acute Myeloid Leukemia and Myelodysplastic Syndrome
This is an open-label, single-center, non-randomized phase I/II pilot study evaluating proton-based Total Marrow Irradiation (TMI) as part of the conditioning regimen prior to allogeneic hematopoietic stem cell transplantation (allo-HSCT) in adult patients with high-risk or relapsed/refractory acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). These patients have an unfavorable prognosis with standard conditioning approaches. Participants will receive a standard conditioning regimen consisting of either myeloablative or reduced-intensity chemotherapy, selected according to age and comorbidities, combined with proton TMI delivered at a total dose of 12 Gy in three fractions. Graft-versus-host disease (GvHD) prophylaxis will be administered according to institutional standards, preferentially using post-transplant cyclophosphamide. Patients will subsequently undergo standard allo-HSCT and will be followed for at least 24 months after transplantation. The primary objective of the study is to assess the safety and tolerability of proton TMI added to standard conditioning, as measured by non-relapse mortality and treatment-related toxicity within the first 100 days after transplantation. Secondary objectives include evaluation of engraftment kinetics, incidence of relapse, overall and relapse-free survival, GvHD outcomes, and quality of life. Study outcomes will be analyzed descriptively and compared with a matched historical cohort.
• Underlying diagnosis of acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS),
• A) Acute Myeloid Leukemia (AML), meeting at least one of the following criteria:
• i. Relapsed disease after a prior complete remission (CR) or
• ii. Disease refractory to at least two cycles of intensive chemotherapy or
• iii. High-risk AML in complete remission (CR), defined by at least one of the following:
• iii a) Adverse molecular or cytogenetic risk according to ELN 2022 classification or
• iii b) Presence of measurable/minimal residual disease (MRD).
• B) Myelodysplastic Syndrome (MDS), meeting at least one of the following criteria:
• i. Relapsed MDS with increased blasts (MDS-IB) or
• ii. MDS-IB2 without reduction of bone marrow blasts below 10% after induction chemotherapy or after at least two cycles of azacitidine or
• iii. IPSS-M score \> 0.5 (high-risk or very high-risk disease).
• Eligibility confirmed by the institutionalal Transplant Indication Committee according to standard criteria.
• Age ≥ 18 years and ≤ 65 years
• Ability to understand and voluntarily sign written informed consent